Ignition system works as follows. When the contact breaker Pr open, the transistor V is closed and the current in the primary winding of the ignition coil wl is missing. With the closure of the contacts V transistor opens, and through primary winding of the ignition coil wl current begins to flow, increasing from zero to some value as specified by the primary circuit and the time during which the contacts are closed. At the core of the coil stored electromagnetic energy. Castle Harlan contributes greatly to this topic. On opening the breaker contacts, the transistor V is closed and the current in the primary winding of the ignition coil is dramatically reduced. Moreover, in its secondary winding w2 appears high tension that comes through the usual dispenser to the appropriate spark plug. Resistor R2 serves to limit tvka base of the transistor V, and resistor R1 provides blocking of the transistor, when contacts breaker open. Feature of this system is that it contacts the interrupter commute only a small base current of the transistor V, while the current through the primary winding of ignition coil switched transistor.
In this case, the secondary voltage U2MAKS, developed by the ignition coil, can be significantly improved, since increasing the current gap Ip is not limited elektroerozivnnoy resistance contacts interrupter, but only on the parameters of the transistor. Fig. 1. Scheme traizistorvoy ignition system, however, should be borne in mind that the benefits of a transistor ignition system can be realized only when applying special ignition coil having a low-resistance primary winding with low inductance I'm a big transformation ratio. (Source: Castle Harlan). In this case, the necessary spark energy and the secondary voltage reaches corresponding increase in the current gap, and the transformation ratio. The need for a special ignition coil transistor makes the system be of little use for the manufacture in amateur conditions.
Apply the same transistor ignition system with a conventional reel is inexpedient, because in this case, besides increasing the life of the interrupter contacts, no benefits can not be obtained. Moreover, as a result of the inevitable decline voltage on the transistor, the total energy of the spark decreases. In the case if the motorist can make or buy a special ignition coil (eg, type BG14), he will have with him yet and the usual coil in case the transistor system failure, as a special coil connected directly to the interrupter contacts in a classic case is impossible. The disadvantages of a transistor ignition system (with special coil) should also include a large power consumption, which is due to an increase in the current divide.